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Switching to LED means more than just switching on the light


Forget about only getting the X-factor with LED's in your tomato greenhouse. No, LEDs are part of a new system that gives access to new capabilities, such as climate fine-tuning, saving energy and slides with plant data. The limitation of a heat surplus due to radiant heat of SON-T lamps no longer exists.
For a number of years now we have been doing tomato trials at the Delphy Improvement Center in Bleiswijk. There we compare a combination of GreenPower LED toplighting and GreenPower LED interlighting with conventionally illuminated businesses in practice. After the coarse Merlice vine tomatoes we started with the second cultivation of Juanita vine cherry tomatoes. It is great that we get high production, good quality and taste, but I would actually like to have you consider the flexibility that a 100% LED lighting system provides.
LEDs are part of a new system that gives access to new capabilities, such as climate fine-tuning, saving energy and slides with plant data.

For example, thanks to the LEDs, last year we planted in mid-August (week 33) and again this year. Such a planting date is early for a company with a SON-T lighting system. At times when the outside temperatures are high and you want to illuminate, the radiant heat emitted by these lamps is a barrier. The much "cooler" LED's do not have that limitation and, in particular in the fall, when the days get shorter, you can still illuminate enough. We have found that such a strategy produces a strong crop that can make it through the winter. Despite high stem densities, the crop was very vital in spring, while I saw crops with a lot of 'wear' that were grown with SON-T lighting.

 

In the test department, we work with an energy screen and a diffuse screen. One of the screens was almost always 95% closed in the afternoon during the lighting period, as of 2:00 PM. When the screen was closed, we dehumidified the greenhouse air as much as possible by keeping the air frames above the canopy open. And what turned out? The crop actually did not require a high room temperature to keep up its speed. Avoid radiation, so as to maintain the plant temperature, and here sufficient dehumidification is the key. In addition, more CO₂ remained in the greenhouse.

 

I think it is great that we have achieved a production of 38.6 kg per m². What is just as nice, I think, is that gas consumption remained at 35 m³ per m². Thus, we have shown that with 100% LED, we can also achieve top production in an energy efficient manner. Lighting with LEDs does require a different kind of cultivation and application of techniques. Then you can gradually start thinking about limiting and reducing fossil energy. Isn't that a nice result from thinking and acting in a different way than in the past?

Piet van de Baar

Piet Hein van Baar is Plant Specialist Vegetables, focusing on tomato crops as he has been in the tomato industry for 20 years. Piet Hein is closely involved in projects in Western Europe and knows the customers and their greenhouses very well. Piet Hein visits a customer every 6 weeks to keep improving the lighting strategy.